Custom Error Messages?

[mad-coder-365]

Versions:

"@sinclair/typebox": "^0.34.33",
"@fastify/type-provider-typebox": "^5.1.0",

Problem:

I have used SetErrorFunction to add custom errorMessage field but it doesn't work.

import {
  DefaultErrorFunction,
  SetErrorFunction,
} from "@sinclair/typebox/errors";

SetErrorFunction(
  (parameter) =>
    (parameter.schema.errorMessage as string | undefined) ??
    DefaultErrorFunction(parameter),
);

export const SignInSchema = {
  body: Type.Object(
    {
      email: Type.String({ format: "email", errorMessage: "Email is invalid" }),
      password: Type.String({ minLength: 6 }),
    },
    { additionalProperties: false },
  ),
  response: {
    204: Type.Null(),
  },
} as const;

Error I get in terminal:

[18:03:20.044] ERROR (24968): Failed building the validation schema for POST: /auth/login, due to error strict mode: unknown keyword: "errorMessage"

I am stuck trying to set custom error messages for my schema. Please let me know how to do this. Thanks!

[sinclairzx81]

@mad-coder-365 Hi,

"@fastify/type-provider-typebox": "^5.1.0",

By default, the Fastify Type Provider uses Ajv under the hood, so Ajv will be responsible for generating error messages. To have TypeBox generate errors, you will need to override the Fastify validation compiler. The TypeBox provider has a Fastify compatible compiler function built in, you just need to enable it using the following.

https://github.com/fastify/fastify-type-provider-typebox?tab=readme-ov-file#type-compiler

I think if you set this up, the, validation errors will flow through SetErrorFunction.

Let me know if this helps
S

[mad-coder-365]

Thanks @sinclairzx81 , it worked. Is there a way to make "errorMessage" appear in vs code intellisense? like other properties like format, minLength etc?

[mad-coder-365]

Never mind got it working by adding it to the typebox module interface